Transcript Revealing the reef

On Web version, right click on
the screen and choose “Edit
slides” to view supporting text
Revealing the reef:
marine life settling on ex-HMS
Scylla
Keith Hiscock
Last updated: 9th March 2009
Get this presentation: www.marlin.ac.uk/learningzone/scylla
Including information from the Settling on Scylla project
The presentation:
• How Scylla was before sinking on 27 March 2004.
• What could we expect: experience from other
artificial reefs.
• The ‘time-line’ of marine life settlement.
• How you can help maintain records from Scylla –
and get involved in reporting marine life
observations.
(All with thanks to: Plymouth Sound BS-AC; MCS local group especially
Amy Bugg; Sally Sharrock; Peter Messenger; University of Plymouth
Diving Centre, Unicomarine for identification of samples, and many
others for the diving, the marine life records and the use of images.
And, of course, the National Marine Aquarium for putting Scylla on the
seabed - right-way-up.)
19
November
2003.
Devonport
Inspection
of existing
fouling
Oysters,
sponges,
barnacles
etc. on one
of the
propellers
27 March 2004
www.national-aquarium.co.uk
Other UK artificial reefs: Poole Bay
(See: Jensen, A.C. & Collins, K.J., 1995, The Poole Bay artificial reef project.
Biologia Marina Mediterranea 2, 111-122.)
Images courtesy of Antony Jensen
Other UK artificial reefs: Poole Bay
(From: Jensen, A.C. & Collins, K.J., 1995, The Poole Bay artificial reef project.
Biologia Marina Mediterranea 2, 111-122.)
Other UK artificial reefs: MV Robert at
Lundy (sunk, January 1975, survey 1980)
Starboard (horizontal) side: 192
taxa (species or species groups)
sampled from 1.4 sq. m; 39 taxa
by observation; 29 taxa in c. 1
sq. m of close-up photographs.
Other UK artificial reefs: local wrecks
Persier
Scylla. In the first year:
1. a small numbers of potentially resident fish (poor
cod) were attracted after about 10 days;
2. colonisation by barnacles, tube worms, Obelia
hydroids and microbial slime occurred within about four
weeks;
3. ‘wandering’ species find the reef (spiny starfish,
spiny spider crabs, long-spined sea scorpion etc.);
4. barnacles, tube worms and Obelia hydroids
became common at about 6-7 weeks and are joined
by Tubularia hydroids and, on shallow parts, brown
filamentous algae;
5. by ten weeks after placement, the variety of
organisms was significant and kelp, solitary sea
squirts, anemones etc. had settled.
Poor cod
Colonisation by microbial slime,
barnacles, tube worms and Obelia
hydroids had occurred within about four
weeks
23 April 2004
23 April 2004
Barnacles, Balanus crenatus
Tube worms, Pomatoceros triqueter
9 June 2004
Brown filamentous algae
25 June 2004
Spiny starfish, Marthasterias glacialis
30 July 2004
Keeled tube worms, Pomatoceros triqueter, saddle oysters, Heteranomia squamula etc.
Scylla. In the first year (continued):
6. by 18 weeks, a wide variety of species including
mass settlement of juvenile queen scallops, many
‘decorata’ anemones, extensive growths of Tubularia
hydroids, variety of algae etc. Mussels settling. Tube
worms and solitary sea squirts cover some surfaces.
Algae abundant on upper surfaces;
7. by 24 weeks, green urchins and common starfish
have settled in large numbers;
8. by 30 weeks, juvenile queen scallops abundant
over and in the vessel. Green urchins and common
starfish now abundant and largish.
30 July 2004
Queen scallops settle
18 February 2005
Queen scallop, Aequipecten opercularis inside the vessel
30 July 2004
Decorata anemone, Sagartia troglodytes decorata
9 June 2004
Tubularia hydroid
9 June 2004
Encrusting sea mat, ?Electra pilosa
30 July 2004
Solitary sea squirts, Ciona intestinalis
30 July 2004
Brown alga, Cutleria multifida
30 July 2004
Filamentous red algae
30 July 2004
30 July 2004
Facelina bostoniensis and eggs
25 September 2004
By end of the summer: dense colonisation – but the urchins and starfish have settled
10 November 2004
Mussels, Mytilus edulis
Image: Sally Sharrock
Scylla. In the first year (continued)
By midwinter (40-48 weeks):
9. green sea urchins and common starfish together
with normal seasonal decline have removed algal
growth and much barnacle and tube worm cover;
10. common starfish have removed mussels,
barnacles and, no doubt, other species;
11. the reef looks ‘bare’;
12. plumose anemones are reproducing (by basal
laceration) and are becoming visually dominant near
the bow;
13. calcareous sponges have settled;
14. corkwing wrasse observed ‘holding territory’.
18 February 2005
Green sea urchin Psammechinus miliaris
18 February 2005
Common starfish, Asterias rubens
18 February 2005
Cleaned by urchins & starfish
18 February 2005
Plumose anemone, Metridium senile
18 February 2005
Calcareous sponges, Leucosolenia botryoides & Sycon ciliatum
18 February 2005
Colonisation on below-waterline black paint. Effective antifouling paint
30 January 2005
Corkwing wrasse on the starboard walkway
Scylla. In the first year (continued)
By the end of and after one year (50-55 weeks):
15. much of vessel still very bare (grazed);
16. but, algae have returned;
17. common starfish declining and green sea urchins
possibly less abundant.
19 March 2005
The bow: still very grazed
By the end of one year, we had:
1. recorded (through the year and from various
sources) a total of 53 species on or in Scylla
(excluding surrounding seabed species);
2. been able to track sequence of species
colonisation (and loss) through the year;
3. had a few surprises (unexpected settlements).
In the second year (2005):
losses and gains
1. Grazing much less (sea urchins decline
dramatically, starfish less abundant).
2. Some significant new species settle.
3. Plumose anemones become visually dominant in
many areas.
4. In the reduced grazing regime, tubeworms,
barnacles and foliose algae thrive.
15 July 2005
Urchin midden
7 September 2005
Algae have colonised the foredeck – but a small variety of filamentous species
7 September 2005
Jewel anemones
20 August 2006
Jewel anemones
15 July 2005
Dead mens fingers
20 August 2006
Leathery sea squirts – present from about October 2004, common by 2006
During the winter 2005-6 and into 2006,
visually dominant species expand and
the reef communities begin to stabilize.
1. Plumose anemones are abundant in some areas
2. Dead man’s fingers are common and grow to full
size
3. Leathery sea squirts begin to be conspicuous
But still room for more – especially inside
28 January 2006
Plumose anemones on prop shaft
28 January 2006
Still plenty of room inside
25 March 2006
Ross, Pentapora fascialis
20 August 2006
Omalosecosa ramulosa: a branching sea mat (bryozoan)
30 August 2006
Sea beard, Nemertesia antennina, first seen winter 05/06
18 August 2006
Dead mens fingers now common and nearly full grown (and more have settled)
18 August 2006
Top of the reef colonised by ‘expected’ variety of seaweeds including kelp
20 August 2006
Foredeck colonised by ‘expected’ variety of foliose seaweeds
20 August 2006
Lots more fish by end of summer 2006 – scad off the bow
20 August 2006
The urchins are back! (but not so many) – and a 2006 settlement of dead mens fingers
20 August 2006
The scallops are back! (but not so many)
28 August 2006
Records of dahlia anemones confirmed (Image: Sally Sharrock)
7 October 2006
Sagartia elegans rosea
18 August 2006
Many parts of the outside of the reefs are ‘solid’ with colonisation and a wide variety of
species
18 August 2006
Some parts of the reefs might even qualify as “pretty”
18 August 2006
But, colonisation of the anti-fouling-painted areas restricted to patches where paint has
flaked (under the stern)
By end of August 2006 (from our ‘Wanted’
list of spring 2005 & before ‘Scylla week’):
First seen
June 2005
White sea fingers
First seen
March 2006
Ross
Still looking
Red sea fingers
Still looking
Edible sea urchin
First seen
Sept 2005
Devonshire cup corals
Still looking
Pink sea fan
126 species recorded from Scylla from
observations and photographs
30 August 2006 and during the subsequent Scylla
Week
Sampling the little beasties (worms, crustaceans etc.)
About 84 additional species identified by Unicomarine from
samples taken in Scylla Week, bringing the total number of
species identified on Scylla to about 220
By the end of 2006, most of the species
that were to be visually dominant on the
reef had settled.
But those species had to expand in
abundance and grow in size before
Scylla would qualify as hosting a ‘mature
steel wreck community’.
And some ‘expected’ species were still
unaccounted for.
27 April 2007
Red sea fingers were first seen in April 2007
17 August 2007
Orange pumice bryozoan, Cellepora pumicosa were first observed in late summer
2006 and, unexpectedly, became extremely abundant in the next year.
15 June 2007
By summer 2007, established species characteristic of wrecks were growing
towards full size: dead man’s fingers, ross and orange pumice bryozoans were
abundant
19 September 2008
Sea urchins, Echinus esculentus were not reported from the reef until 30
September 2007
10 December 2008
Seafans, Eunicella verrucosa, settled in about July 2007 – and some grew rapidly
19 September 2008
Feather stars, Antedon bifida only became abundant in 2008
10 December 2008
There are significant seasonal changes on Scylla – winter scene with few algae on
shallow decks
10 December 2008
Two of the conspicuous characterising animals, species of oaten pipe hydroids,
are devastated by sea slugs in summer and die back in late-winter.
26 February 2009
Spring growth beginning – sea beech Delesseria sanguinea
26 February 2009
Topknot ‘braving’ the anti-fouling paint under the stern
By end of March 2009 (from our ‘Wanted’
list of spring 2005 & after ‘Scylla week’):
First seen
June 2005
Dead man’s fingers
First seen
March 2006
Ross
First seen
April 2007
Red sea fingers
First seen
Sept 2007
Edible sea urchin
First seen
Sept 2005
Devonshire cup corals
First seen
August 2007
Pink sea fan
258 species recorded from Scylla from
observations, photographs and samples
Some species are expected to increase
in abundance over the next few years:
Fish, especially wrasse
Edible sea urchins
Devonshire cup corals
We are still waiting to see some species
that occur commonly on steel wrecks in
south Devon and Cornwall:
Lobster
Yellow boring sponge (massive form)
Cotton spinner
Sandaled anemone Actinothoë sphyrodeta
Scylla now hosts (March 2009, five years after placement)
a mature steel wreck wildlife community
Report any unusual or interesting marine
life (supported by images where possible):
MarLIN
24 hr reporting hotline:
01752 255026
E-mail images to: [email protected]
Get this presentation: www.marlin.ac.uk/learningzone/scylla
Join-up: www.mcsuk.org; www.seasearch.org.uk